Bypass DNS with curl --resolve troubleshooting
Pin host to a specific IP to test backend while keeping SNI/Host header
curl -sv --resolve <host>:443:<ip> https://<host>/healthz
more troubleshooting
all 32 commands →
In-cluster DNS smoke test
kubectl run dnsutils --image=tutum/dnsutils -it --rm --restart=Never -- nslookup kubernetes.default
Query CoreDNS directly
dig +short @$(kubectl -n kube-system get svc kube-dns -o jsonpath='{.spec.clusterIP}') <name>.<ns>.svc.cluster.local
Inspect CoreDNS config and logs
kubectl -n kube-system get cm coredns -o yaml; kubectl -n kube-system logs deploy/coredns --tail=50
TLS cipher and protocol enum
nmap --script ssl-enum-ciphers -p 443 <host>
Verify full TLS chain and SNI
openssl s_client -connect <host>:443 -servername <host> -showcerts 2>/dev/null | grep -E 'Verify|s:|i:'